How to Break into Quantitative Research?

I’m a CS master’s student from a top 5 school, and I’ve done some interesting theoretical research in deep learning. I wanted to try out quant research, maybe in an intern capacity, as I’ve been studying applied math and also have managed fo get into a solid master’s program for the subject. Do you have any tips on what to study, how to get interviews, and how to score an intern spot at a place like Two Sigma, Citadel, DE Shaw, etc?

I really appreciate the guidance!